Some fairly stable organic compounds having a .pi. electron conjugation system, such as polyacetylenes, polythiophenes and polypyrroles, have been reported. Recently, apart from homopolymers, copolymers of this type have also been synthesized such as those obtained from thiophene and pyridine, and as they have a unique UV absorption spectrum due to their intramolecular electron donor-acceptor structure, it is hoped that they will find application as new functional materials.
The silole skeleton, on the other hand, is a structure which can function as either an electron donor or an electron acceptor, and although investigations have been made with a view to applying it to polymers, the studies carried out to date have been inadequate.
The Inventors attempted to introduce the silole skeleton into polythiophenes, and thereby discovered a stable thiophene-silole copolymer having a light absorption band in the visible region.